Archaeologists in Brazil study 7000-year-old rock carvings revealed during the Amazon region's current drought.
Archaeologists find a silver lining to Brazil's drought.
Extremely low waters reveal ancient stone etchings in Manaus, northern Brazil.
Typically hidden below the Rio Negro, the rock carvings could be as old as 7,000 years.
The river, which flows into the Amazon, is at its lowest in more than a century.
Local resident Walter Calheiros, who discovered the etchings, rushed to photograph them before the dry season ends this month.
Archaeologists say the finding reveals humans used the area much earlier than previously thought.
(SOUNDBITE) (Portuguese) ARCHAEOLOGIST RAUNIR VALE FROM THE UNIVERSITY OF SAO PAULO, SAYING:
"We need to think of this entire rock formation as a cultural landmark for analysis, not just these marking, but the whole thing in context, here in front of the meeting of the waters, with a large amount of ceramic sites behind here dating to some 2,000 years. There are a number of relevant items within this context and these marking are just one element of it. We need to think not only of the cultural markings but of the cultural landscape."
The drought follows last year's widespread flooding - with some scientists blaming global warming for the severe weather patterns plaguing the Amazon region.